In combat zones of the battlefield of today, military personnel are provided with better body protection, faster evacuation and improved medical technology and assistance. As a result, there have been dramatic reductions in battlefield mortality. However, the arms and legs of military personnel remain vulnerable to the ammunition used in today's war zones. Combat trauma to an unprotected arm or leg is often caused by high energy impact resulting in extensive soft tissue damage. Lower leg, foot and ankle injuries in the battlefield can also put soldiers at increased risk of further harm by limiting their mobility. Also, due to the severe nature of war wounds, reconstructive procedures often are delayed until months after the initial injury. After evacuation, but during the evaluation period prior to reconstructive surgery, assistive devices providing the person with mobility and independence are needed, particularly those that allow usage of the limb, as well as functional use of the upper extremities by eliminating the need for crutches and wheel chairs.
Lower leg, foot and ankle injuries have been a problem for not just the military but for the civilian population and industry as well. The National Center for Health Statistics has reported that approximately 59 million Americans have some type of foot problem and the frequency of ankle injuries in the United States varies from 1 to 10 million per year. Some of the major everyday living injuries include: automobile accidents, where 16% of occupants of passenger vehicles who were hospitalized following motor vehicle crash injuries, were diagnosed with a serious lower extremity injury and the injuries; workplace injuries, occurring at a rate of nearly 400 foot injury cases a day; and sports injuries and other activity related injuries, where the ankle is the most commonly injured joint among athletes. Such every day living injuries are further exacerbated by demographic trends such as an active aging population, diabetes and obesity.
Mobility impairment is the most frequent reason for using an assistive device. An estimated 7.4 million persons in the U.S. household population use assistive technology devices for mobility impairments. Assistive devices include crutches, canes, walkers, medical shoes and wheel chairs. Anyone ever sustaining an injury requiring crutches understands that long-term crutch use is uncomfortable, and can cause chronic shoulder pain, arthritic conditions, discomfort, muscle weakness and fatigue, and injuries to underarm arteries.
For some patients, lower extremity health problems become so severe that they must use a wheelchair. Certainly, the chronic effects of trauma or medical conditions that impair lower limb function can result in substantially decreased productivity and quality of life. In the past, lower limb orthoses provided stability, but the energy efficiency and long-term ergonomics were hindered by the rigidity of the structures. Modern orthoses provide more natural, energy efficient, and more comfortable gait by utilizing compliant materials to passively facilitate energy storage and release during locomotion. Powered orthoses, such as those disclosed in U.S. Pat. No. 7,416,538 and WO 2004/017890, also enable further advances in orthotic technology. However, improved powered orthoses enabling individuals with lower-leg injuries to walk with the same speed, energy efficiency and comfort as uninjured individuals, are desired.